In the past, the modulation formats used in mobile communication systems were limited by the radio frequency (RF) power amplifier efficiency. However, with the advances in transistor technology and amplifier topology, this limitation has been overcome and modulation formats with high efficiencies have now become the norm.
The Doherty power amplifier (DPA) is widely adopted in modern third generation (3G) and fourth generation (4G) wireless communication systems, primarily because it offers additional efficiency peak at back-off. This additional efficiency peak allows higher amplifier efficiencies at output back-off region, and as a result, a significant reduction in power consumption can be achieved (as these amplifiers are one of the main power consumers in these systems).
To date, the bandwidth remains a limiting factor for DPAs.